Polyolefins such as low density polyethylene (LDPE) and polypropylene (PP) are commonly used in many non-crosslinked foam applications. For example, U.S. Pat. No. 6,583,193 discloses an extruded, coalesced polypropylene foam that is either open-celled which is useful for sound insulation applications or close celled which is useful for thermal insulation applications. LDPE or PP can also be blended with a softer component such as copolymer of ethylene and vinyl acetate (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA) and other ethylene copolymers having a low melting point to make soft foams for a variety of applications. For example, U.S. Pat. No. 6,590,006 discloses macrocellular foams comprising a blend of a high-melt-strength (HMS) polypropylene and an ethylene copolymer such as EVA, EEA, and EAA for use in sound absorption and insulation applications.
Although there are many useful polymers and polymer blends for soft foam applications, there are always needs for improved soft foams because of the continuous demands of product improvements by the consumers and foam manufacturers.